First let me say i DO NOT own this so i can't help you
1.go to https://freeminecrafthost.com/

2.hit register and fill out the form MAKE SURE YOU USE YOUR MINECRAFT USERNAME AS YOUR USERNAME

3.once you signed up and everything click user panel and click start server

sometimes you may get this

if you do try again later
you now have a server running
by default you only have up to 4 players but if you hit the upgrades tab you can buy more things
i.e up to 12 players, more ram, custom maps, plugins

sorry for big pics